But avoid foolish questions There is no necessity for debating long about the exposition of this passage. He contrasts "questions" with sound and certain doctrine. Although it is necessary to seek, in order to find, yet there is a limit to seeking, that you may understand what is useful to be known, and, next, that you may adhere firmly to the truth, when it has been known. Those who inquire curiously into everything, and are never at rest, may be truly called Questionarians. In short, what the schools of the Sorbonne account worthy of the highest praise -- is here condemned by Paul; for the whole theology of the Papists is nothing else than a labyrinth of questions. He calls them foolish; not that, at first sight, they appear to be such, (for, on the contrary, they often deceive by a vain parade of wisdom,) but because they contribute nothing to godliness. When he adds genealogies, he mentions one class of "foolish questions;" for instance, when curious men, forgetting to gather fruit from the sacred histories, seize on the lineage of races, and trifles of that nature, with which they weary themselves without advantage. Of that folly we spoke towards the beginning of the First Epistle to Timothy. [1] He properly adds contentions; because in "questions" the prevailing spirit is ambition; and, therefore, it is impossible but that they shall immediately break forth into "contention" and quarrels; for there every one wishes to be the conqueror. This is accompanied by hardihood in affirming about things that are uncertain, which unavoidably leads to debates. And fightings about the law He gives this disdainful appellation to those debates which were raised by the Jews under the pretence of the law; not that the law of itself produces them, but because the Jews, pretending to defend the law, disturbed the peace of the Church by their absurd controversies about the observation of ceremonies, about the distinction of the kinds of food and things of that nature. For they are unprofitable and unnecessary In doctrine, therefore, we should always have regard to usefulness, so that everything that does not contribute to godliness shall be held in no estimation. And yet those sophists, in babbling about things of no value, undoubtedly boasted of them as highly worthy and useful to be known; but Paul does not acknowledge them to possess any usefulness, unless they tend to the increase of faith and to a holy life.

Footnotes

1 - See [21]p. 23.

But avoid foolish questions and genealogies - See the 1-Timothy 1:4 note; 2-Timothy 2:16, 2-Timothy 2:23 notes.
And contentions, and strivings about the law - Such as the Jews started about various matters connected with the law - about meats and drinks, etc.; the notes at 1-Timothy 1:4; compare the notes at Acts 18:15.
For they are unprofitable and vain - - They disturb and embitter the feelings; they lead to the indulgence of a bad spirit; they are often difficult to be settled, and are of no practical importance if they could be determined. The same thing might be said of multitudes of things about which men dispute so earnestly now.

Avoid foolish questions, and genealogies - In these the Jews particularly delighted; they abounded in the most frivolous questions; and, as they had little piety themselves, they were solicitous to show that they had descended from godly ancestors.
Of their frivolous questions, and the answers given to them by the wisest and most reputable of their rabbins, the following is a specimen: -
Rabbi Hillel was asked: Why have the Babylonians round heads? To which he answered: This is a difficult question, but I will tell the reason: Their heads are round because they have but little wit.
Q. Why are the eyes of the Tarmudians so soft?
A. Because they inhabit a sandy country.
Q. Why have the Africans broad feet?
A. Because they inhabit a marshy country. See more in Schoettgen.
But ridiculous and trifling as these are, they are little in comparison to those solemnly proposed and most gravely answered by those who are called the schoolmen. Here is a specimen, which I leave the reader to translate: -
Utrum essent excrementa in Paradiso? Utrum sancti resurgent cum intestinis? Utrum, si deipara fuisset vir, potuisset esse naturalis parens Christi?
These, with many thousands of others, of equal use to religion and common sense, may be found in their writings. See the Summa of Thomas Aquinas, passim. Might not the Spirit have these religious triflers in view, rather than the less ridiculous Jews? See the notes on 1-Timothy 1:4; 2-Timothy 2:23 (note).
Contentions, and strivings about the law - Of legal contentions, and different and conflicting decisions about the meaning of particular rites and ceremonies, the Talmud is full.

But avoid foolish questions,.... Such as were started in the schools of the Jews; see 2-Timothy 2:23
and genealogies; of their elders, Rabbins, and doctors, by whom their traditions are handed down from one to another, in fixing which they greatly laboured; see 1-Timothy 1:4 and contentions and strivings about the law; the rites and ceremonies of it, and about the sense of it, and its various precepts, as litigated in the schools of Hillell and Shammai, the one giving it one way, and the other another; and what one declared to be free according to the law, the other declared forbidden; which occasioned great contentions and quarrels between the followers of the one, and of the other, as both the Misna and Talmud show: and agreeably to this sense, the Syriac version renders it, "the contentions and strifes of the scribes"; the Jewish doctors, who were some on the side of Hillell, and others on the side of Shammai; as well as went into parties and strifes among themselves, and oftentimes about mere trifles; things of no manner of importance; wherefore it follows,
for they are unprofitable and vain; empty things, of no manner of use, to inform the judgment, improve the mind, or influence the life and conversation.

avoid--stand aloof from. Same Greek, as in 2-Timothy 2:16; see on 2-Timothy 2:16.
foolish--Greek, "insipid"; producing no moral fruit. "Vain talkers."
genealogies--akin to the "fables" (see on 1-Timothy 1:4). Not so much direct heresy as yet is here referred to, as profitless discussions about genealogies of aeons, &c., which ultimately led to Gnosticism. Synagogue discourses were termed daraschoth, that is, "discussions." Compare "disputer of this world (Greek, 'dispensation')."
strivings about the law--about the authority of the "commandments of men," which they sought to confirm by the law (Titus 1:14; see on 1-Timothy 1:7), and about the mystical meaning of the various parts of the law in connection with the "genealogies."